Compatibility Overview
Harlequin Rasbora and Otocinclus can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges, and neither poses a major aggression risk to the other. A minimum 40-gallon tank is recommended to provide adequate territory and water volume for both species.
| Factor | Harlequin Rasbora | Otocinclus | Verdict |
|---|---|---|---|
| Temperature | 72–81°F | 72–82°F | ✅ 72–81°F |
| pH Range | 5.5–7.5 | 6.0–7.5 | ✅ 6.0–7.5 |
| Temperament | peaceful | peaceful | ✅ Compatible |
| Adult Size | 1.75 in | 1.5 in | ✅ Similar |
| Min. Group | 8+ | 4+ | See below |
| Min. Tank Size | 40 gallons (for both species) | — | |
✅ Compatibility Positives
⚠️ Caution Points
Species Profiles
Harlequin Rasbora — Trigonostigma heteromorpha
Active mid-level schooling fish with a distinctive black triangular patch. One of the best all-around community tank fish.
→ Full Harlequin Rasbora care guide
Otocinclus — Otocinclus spp.
Tiny algae-eating catfish that are peaceful with all species. Need established algae growth and biofilm; sensitive to ammonia.
Frequently Asked Questions
Can Harlequin Rasbora live with Otocinclus?
Yes, in a well-planned setup. Harlequin Rasbora and Otocinclus can generally share an aquarium with appropriate planning. Both species prefer overlapping temperature and pH ranges, and neither poses a major aggression risk to the other. A minimum 40-gallon tank is recommended to provide adequate territory and water volume for both species.
What tank size do I need for Harlequin Rasbora and Otocinclus together?
A minimum of 40 gallons is recommended for keeping Harlequin Rasbora and Otocinclus together. A larger tank improves water stability and reduces territorial conflict.
What temperature suits both Harlequin Rasbora and Otocinclus?
72–81°F
Is a Harlequin Rasbora aggressive toward a Otocinclus?
Harlequin Rasbora is peaceful and Otocinclus is peaceful. No major aggression issues are expected between these species.